Self-quench superregenerative receiver



Oct. 28, 1952 RlCHMAN SELF-QUENCH SUPERREGENERATIVE RECEIVER Filed Nov. 28, 1947 v o 5:55 gm 65:35 -053 3 INVENTOR. DONALD RICHMAN ATTORNEY Patented Oct. 28, 1952 ELE-QUENCH EGENERATI E RECEIVER Donald Richman, New York, N. 1. assignor to Hazeltine Research, Inc., Chicago, Ill., a'corporation of Illinois Aprl i ation ovember 94 Ser al No. 788 65 6 Claims. 1

The present invention is directed to self quench superregenerative receivers adapted ior operation in'the saturation-levelmode and, particularly, to such receivers having operating Characteristics which are stabilized with respect to variations of the operating conditions to which they are normally' subjected in operation Superregenerative receivers of both the separately quenched and the self-quench type have found Wide utility due to their exceedingly high sensitivity, extreme simplicity and inexpensive construction. The operating characteristics of many such receivers may, however, become quite unstable with variations of the operating conditions to which they are normally subjected in operation. For-- example, the variations of the value of the conductance of the resonant input circuit of the superregenerative receiver due to antenna loading thereof, changes in the value of the receiver circuit components due to aging, changes of the transconductance of the regenerator tube over the operating life thereof, variations of the energization of the receiver circuit, and tuning of the receiver from one wave-signal station to another having different wave-signal intensities may materially alter the operating characteristics of the superregenerative receiver.

Superregenerative receivers of the separately quenched type and characterized by relatively high stability of their operating characteristics have been proposed to avoid some of the foregoing difiiculties. One such receiver employs a time-constant network in the input circuit of the regenerator tube thereof for developing therein a bias potential which is adapted to maintain the average anode-current pulse width substantially constant with variations of operating conditions to which the separately quenched superregenerative receiver is subjected. For some purposes, however, for example those applications wherein it is advantageous to effect a saving in the number of electron tubes and other electrical components, it is desirable to employa self-quench superregenerative receiver yet it is usually further desirable that the receiver have high stability of its operating characteristics with respect to changes in the operating conditions experie enced thereby. It may also be desirable that a receiver of this type exhibit certain other particular characteristics, such as controlled selectivity independent of the quench rate, which is notinherent in the usual self-quench superregenerative receiver. These requirements are (iii: ficult to obtain in a self-quench superregenerative receiver for reasons which will be stated hereinafter.

In a, e aratel quench d uper s ne i e r c i r the sel cti i is ord ar l e ne b the wave form of the quench voltage applied thereto and particularly by the wave form in the vicinity of maxirr um sensitivity. The desired Wave form may usually be secured by suitable de-- sign and adjustment of the quench-voltage generator. A self-quench superregenerative receiver develops its own quench voltage, however, and the attainment of a quench voltage having a particular Wave form is considerably more difficult in this type of receiver. Any selection or adjust-. ment of its circuit parameters to provide the desired quench-voltage Wave form may considerably influence or modify the self-quench frequency in a manner which tends to impair the stability or modulation handling capacity of the receiver. Thus the design of a self-quench superregenerative receiver having high stability of its operating characteristics over a wide range of variation of operating conditions presents a rather unusual problem.

Superregenerative receivers, of both the separately quenched and self-quench types, characterized by high stability of the operating characteristics thereof over a wide range of variations of operating conditions are disclosed and claimed in th copending application of Bernard D. Loughlin, Serial No. 753,236, filed June '7 1947, entitled Superregenerative Receiver and 2.5-, signed to the same assignee as the present invention. The superregenerative circuits or these receivers employ a regenerator tube having a timeconstant network degeneratively included in a circuit portion common to the input and output circuits Of the, tube., This network is efiective the self quel ch type of circuit, for example, to maintain the average self-quench periodicity of the superregenerative receiver substantially constant. It-does this by developing from variations of the anode current of the regenerator tube a control effect which maintains the average anod current of the regenerator tube substantially constant with variations of normal operating conditions. While excellent stabilizin action of a self-quench superregenerative receiver may be obtained in this manner, it has been 618'. termined that stabilization may not be quite as efiective as desired under some rather severe operating conditions such as those imposed by a 7 high quench rate ora 10W anode-supply voltage,

This is partly due to the Wave form of the individual periodic pulses of anode current which develop the control effect and provide the stabilize v ,ing action for the self-quench superregenerative receiver. Each of the anode-current pulses comprises two portions. The first portion has a relatively low amplitude and usually a substantial duration and occurs during the oscillatory buildup interval, while th second portion has a considerably greater amplitude and ordinarily a much shorter duration and occurs during the saturation-level interval. The integrated values of these two portions determine the average value of anode current for any given value of selfquench frequency. If the two portions retain their wave shape with variation of the selfquench frequency, then it is apparent that the average anode current varies only with the number of anode-current pulses per second and thus only with the self-quench frequency. It has been determined in practice that when the quench frequency tends to change due to vary wide varia-v tions of the operating 'conditions of the selfquench superregenerative receiver, the low amplitude-long duration portion of each anodecurrent pulse may vary both in amplitude and duration. Accordingly, under some severe operating conditions this variation of the shape or area of the first portion of each anode-current pulse may represent a considerable part of the total value of each anode-current pulse. Hence, in spite of changes in the quench frequency, the average value of the anode current of the regenerator tub of the receiver may not tend to change sufficiently with the changes experienced in the operating conditions to develop the necessary control effect across the degenerative timeconstant network for maintaining the average self-quench periodicity of the superregenerative receiver substantially constant.

.The previously described arrangement of Bernard D. Loughlin, which derives its stabilizing action from the anode-current pulses flowing through the regenerator tube, includes an impedance in the anode-energizing circuit which reduces the voltage applied between the anode and the cathode of the tube. In special applications which require a high quench rate or which have available only a low-voltage anode-energizing source it may be necessary that the available voltage between the anode and the cathode of the regenerator tube be as large a proportion of the total anode voltage as possible. The abovementioned impedance, therefore, limits the degree of stabilization which may be obtained in the previously described arrangement.

It is an object of the invention, therefore, to provide a new and improved self-quench superregenerative receiver which possesses the desirable operating characteristics above enumerated.

It is another object of the invention to provide a new and improved self-quench superregenerative receiver characterized by an exceptionally high stability of operating characteristics over a very wide range of variations of operating conditions to which the receiver is normally subjected during operation.

It is a further object of the invention to provide a self-quench superregenerative receiver having improved amplification or gain yet one which at the same time possesses high stability of its operating characteristics over widely varying 4 of operation to which it is normally subjected in practice.

It is yet another object of the invention to provide a self-quench superregenerative receiver which requires but a relatively low-voltage anodeenergizing source yet has an exceptionally high stability of operating characteristics over a very wide range of variations of operating conditions to which the receiver is normally subjected during operation.

In accordance with a particular form of the invention, a self-quench superregenerative receiver comprises a regenerative circuit adapted to have a modulated wave signal applied thereto and including a regenerator tube having anode, cathode, and control electrodes. The receiver also includes an electrical time-constant network coupled to the cathode electrode and having a periodic potential developed thereacross in re sponse to an electrode-current flow of the regenerator tube for effecting periodic self-quenching of the regenerative circuit to provide superregenerative amplification of the applied wave signal. The parameters of the regenerative circuit and the electrical time-constant network are so proportioned that the oscillatory amplitude of the circuit extends to a saturation-level mode of operation thereof during an interval of each quench cycle. The receiver also includes an electrical time-constant network having atime constant longer than that of the first-mentioned network coupled in circuit with the regenerative circuit between the control electrode and the cathode electrode and responsive to control-electrode current of the regenerator tube flowing only during the saturation-level intervals to develop across the second-mentioned network for appli cation to the control electrode a gain-control potential eifective to stabilize the operating characteristics of the receiver against operating conditions which tend to modify the average selfquench periodicity of the receiver. The selfquench superregenerative receiver further in eludes means coupled to a predetermined pair conditions of operation to which it is normally subjected in operation.

It is another object of th invention to provide a self-quench superregenerative receiver which is capable of operation at a high quench rate and yet possesses high stability of its operatin characteristics over widely varying conditions of the aforesaid electrodes for utilizing the modulation components of the applied wave signal derived by the regenerative circuit.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the followin description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring now to the drawing, Fig. l is a circuit diagram, partly schematic, representing a complete self-quench superregenerative receiver embodying the present invention in a particular form; and Fig. 2 comprises graphs utilized in ex plaining the operation of the receiver.

Referring now more particularly to Fig. 1 of the drawing, the self-quench superregenerative re.- ceiver comprises a regenerative circuit 10 including a regenerator tube ll having an anode, a cathode, and a control electrode. The regenerative circuit [0 includes an input circuit l2 coue pled to the control electrode of the tube II and shunted by a damping resistor l3. The input circuit I2 is tunable by an adjustable inductor l5 which is coupled to an antenna system [6. The feedback of energy from the output circuit to the input circuit of tube I l to produce regeneration is provided by a windin l8 included in the-oath;- ode circuit of the tube II and coupled to the inductor l5. The terminal of the'winding l8 opposite its cathode terminal is adapted selectively b onnected tosroundeither throu h-W n54? pole double-throw switch 2 0 or throne-. as. ele= trical time:const.ant network '2! comprising a esistor 23 connected in parallel with a c ndenser 24. 'lEhe switch .20 will be referred to as having two operating positions for the switch blade thereof designated a and b for reasons which Will be made more apparent hereinafter. The 31:- ments of the network 2| have values so selected that in one of the operating positions of the switch 20, namely the position b, the network comprises a self-quench means for developing a voltage thereacross to effect periodic quenching of the regenerative circuit l8 and thereby pro.- vide superregenerative amplification of a modu-v lated wave signal applied to the input circuit l2.

The anode of the tube II is connected to a source of energizing potential, indicated as +13, through a resistor 22 and a radio-frequency choke coil 14 and is also connected to ground through a condenser 25. The choke coil M has a small impedance to signals of quench frequency. 'The resistor 22 and the condenser 25 are represented as being adjustable in order that it may have somewhat different values depending upon the type of self-quench operation desired for the superregenerative receiver. When anode-quench op eration is desired, rather than the cathode-circuit type of quench earlier mentioned, the condenser 25 is quite small so that the potential thereac 'oss may vary suiiiciently to provide the proper quench-voltage wave. When the cathodecircuit or control-electrode circuit type of selfquench operation is employed, the condenser 25 has a larger capacitance than with the anode-circuit type of self-quench operation. For the control-electrode type of quench operation presently to be described, the condenser 25 must also be of suflicient size to constitute a by-pass condenser for the modulation components of the applied wave signal when the audio-frequenc componentsoi the wave signal applied to the superregenerative receiver are to be derived from the control-electrode circuit of tube l I, as will be described subsequently. However, when th modulation components are taken from the anode circuit of the regenerator tube I l, in a manner also to be described hereinafter, the condenser 25 is somewhat smaller in size so as not to comprise a by-pass condenser for the modulation gompenents. The resistor 22; in each instance, is proportion d to provide self-quench operatiqii il the anode-quench circuit arrangements or to provide the proper energizing potential for the re:

generator" u H in he cathode or th ooht oh electrode quench arrangements.

The elf-qu n u s eeeh rsti s receiver a s includes another electrical time-constant network 27 adapted selectively to be included in the" control-electrode circuit of the regenerator tube II for effecting control-electrode circuit selfquenching. This network comprises a condenser 2B, which is connected between one terminal of the tuned input circuit l2 and ground, and a resistor 29, 'lhe resistor 29 is connected between he ohh ed terminal of the condenser i d a m eh e blade 5 of s ne em ie trip1e=ihrow swi ch through a res stor 3?. wh c a b a ju t l .A ou ce positi e bias otential in ca sda FB is com etes ross a v lta e di d r 3 om risin se es e resistors 34 and 57 The l w-potential ih erhie i ten tehtiali n h ehmot htial t rminals of the voltage d r "3. are c nes-fete hisoecti slya o s she switch c ntac s it b and c o th switeh so seleotiven o ement o the blade s11 the e illn ect thes -sto e? to n do re is s t o s -;T

esis w sein su h hat seii q isnoh aet oh poss bl a d t. a time constant longer than the time constant domains of the tuned inp t oi iiit 2, hav uitable val e to provide the desired W shap ch o ts .8.- The res r 29 prefer .a -iz e oi resistan e whi h is mu h greate ,he control electrode-cathode impedanee oi the reeehsnator time durin not-s hen the. con rol electrode is c nductive. i he eesne ative receiver further nclude ano her electrical time-constant etw rk .3 wh ch s re oh e to the control-electrod cu ent .flo z he re n du in the satura on-level in ervals of hereceiver t deve an app y to the c t ol e ect ode of tu e 1 ssainecon roi pote t ef ectiv t sta ilize th perat n characteri ti s he re eiver a st op rat n onditio s which t nd to modify th aver e selfquench periodicity of the receiver. This network m rises the resistor 32 an a c nde ser 8, th

'. a ter be n connected between the juncti n of 1 ff c th cont o ele rode-cat de ias dur n the next quench cycle. The condenser 38 ordiinarily has a su fic ent y l r e cap c tha it as-a low impedanc for urrent of modulationsignal frequencies to prevent a degenerative-action with respect thereto, that is, a capacitance sumoiently la e tha the b as volta e d p d thereacross cannot change appreciably with dynamic changes of control-electrode: current result n fr n d nam c ha g s of s f-qu nch fr quehoy hi h n turn a e cau d b the amp itude modulation gt a received wave signal. The condenser 38 preferably has a large value of capacitance when the switch blade 30 is toengage swit h conta t h b t m y h a bly ma ler e le hen the sw h is to engage h r of the switch on a ts h or o f r reasons h, will become more apparent hereinafter.

Th superregenera-tive receiver further includes means ri ed to a f q i noh net f r rivi; g th mod tion components of a wave sigei ap i d in the ned in u c r uit A tho this m an he cou d to an o th fl l 1 h netwo s, f r s mp ty nl two such e sl n arrangem n are re es n ed.- Qhe arran em n comprises a s e-1 pole double-throw switch 4|, the movable blade adapted to be coupled through a h con act a o h anode of the tribe i! or th i h a second ta ionar swit -f contact? to a as d uor 4.3 w i h s n e ed- ,h siohta t .c of a s n l poie en. The blade 42 of the t9 the input circuit of a con.- techs-h am ifier 45 h ou h a r het orh @fiective t remove ,led to asisn l-reom duee t so i oi conven ional construction.

The siviioh ii inst. m ntioned inc udes a mo abl blade 52 adapted selectively to engage the aforementioned switch contact c, a neutral switch contact a, and a switch contact b wherein the resistor 29 is short-circuited and the quench-frequency determining action of the network 2'I is prevented.

Considering now the operation of the superregenerative receiver just described, it will be assumed initially that switches 20, 3| and II are in the positions indicated in the drawing and that switch 5| is operated to close its contact I). It will; also be assumed that the condenser 25 and the resistor 22 have been adjusted" to proper values. For this assumed condition, the receiver operates as a self-quench superregenerative re-'- ceiver wherein the resistor-condenser network 2| in the cathode circuit of the regenerator tube I I develops the required self-quench voltage and the modulation components of the applied wave signal are derived from the anode-cathode circuit of the tube I I. amplified in unit 45, and applied to the signal-reproducing device 46. Referring now to the curves of Fig.2, it will be assumed, for the purpose of analysis, that a new cycle of self-quench operation begins at time it at which time the signal applied to the tuned input circuit l'2 from the antenna system I6 begins to build up from the amplitude E represented for the modulated wave signal shown in Fig. 2a. The oscillations in the tuned input circuit I2 are regeneratively amplified and build up in amplitude during the oscillation build-up inter-' val tu-ti, as represented by the solid-line curve A which it may be noted is plotted'to a decibel scale on the ordinate axis. The increase of oscillation amplitude continues to a saturation level thereof designated Es. The oscillations in the input circuit 12 continue approximately at this am plitude level during the saturation-level interval i1-tz of the superregenerative circuit. "The duration of the last mentioned interval is determined by the time required for the network 2 I to develop thereacross from the anode-current pulse a bias potential sufiicient to bias regenerator tube II td anode-current cutoff. In particular, the saturation-level interval is established by the time required for the condenser 24 to charge to the value where it produces anode-current cutoff in' tube I I. At time t2, the tube I I is biased to cutofi and the amplitude of the oscillations in the tuned cir-' cuit I2 decreases exponentially to reach at time t3 their original amplitude E as shown by curve A. As soon as the tube I I becomes nonconductive at time t2, the condenser 24 of the network 2| begins to discharge through the resistor 23. The duration of the discharge interval tzf-tg is es: tablished by the time required for the condenser 24 to discharge sufficiently to permit the regenerator tube I I again to become conductive and initiate a new cycle of operation similar to that just described.

The envelope of the oscillations developed in the tuned circuit I2 during the cycle of operation just described is represented by the solid-line curve B of Fig. 2b. The anode-current now through tube II is of somewhat irregular pulse wave form as represented by the solid-line curve C of Fig. 20. It will be noted that the anode! current pulse comprises a firstportion P1 of rela'-' tively low amplitude which occurs during the build-up interval to-t; andasecond portion P2 of relatively large amplitude occurring during the saturation-level interval h-tz. During the last mentioned interval, the control electrode of tube II becomes conductive and the resulting control electrode-cathode rectification of the oscillations developed in the input circuit I2 takes place A roughly symmetrical control-electrod current pulse is thereby produced, as represented by the solid-line curve D of Fig. 2d. Although the duration of the pulse is very slightly shorter than that of the second portion P2 of the anode-current pulse C, the control-electrode current pulse is represented as having a duration corresponding substantially thereto to simplify the illustration.

. It will be clear from the above-described operation that the self-quench period of the superregenerative receiver comprises the sum of the oscillatory build-up interval to-ti, the saturationlevel interval 231-732, and the discharge interval t2-t4. It will be manifest that if any one of these three intervals changes, the quench period varies accordingly. The saturation level of the super; regenerative circuit has an approximately constant value, since it is established by the receiver parameters, and thus determines the amplitude of each pulse of anode current. The saturationlevel interval Iii-t2 may be considered as approximately constant in duration since it is established by a constant amplitude anodecurrent pulse and by the time required for the cathode-circuit condenser 24 of constant capacitance to charge. The discharge interval 162-754 is effectively constant since it is determined by the discharge time constant of the condenser 24 and the resistor 23 of the self-quench network 2I. Consequently, asa first order approximation, the quench period can be considered to vary only with a change in the build-up interval to-ti. In a conventional selfquench superregenerative circuit, the build-up interval efiectively becomes shorter with increasing amplitude of the applied wave signal. This is because the oscillations in the tuned input circuit have an increasingly larger initial amplitude so that smaller intervals of time are required for the amplitude of the oscillations to build up to the saturation-level value. For example, if it be assumed that in a conventional self-quench superregenerativ circuit the amplitude of the applied wave signal has a larger value E, as indicated in Fig. 2a, the oscillatory build-up inter val is shortened to the new value i041. This in turn causes the termination of the saturationlevel interval to be advanced to the moment t2 and also the termination of the discharge interval to be advanced to the moment t4. Accordingly the increased amplitude of the applied wave signal causes the self-quench period of a conventional self-quench superregenerative circuit to be decreased from its initial value 15044 to a new value t0-t4'. I

Under the assumed conditions last mentioned, namely that the regenerative circuit I0 operates as a conventional self-quench superregenerative circuit and has a larger amplitude wave signal applied thereto, the manner of the oscillation build-up in the tuned input circuit I2 for a wave signal having the amplitude E is now represented by the broken-line curve A of Fig. 2, the amplitude envelope of the oscillations by the brokenline curve B, and the anode current and the control-electrode current of the regenerator tube II by the respective broken-line curves C and D. v Thus in a conventional self-quench type of. superregenerative receiver, the quench period decreases with increasing wave-signal amplitude. Th1s decreasing quench period, which corresponds to an increasing quench frequency-causes the average value of the anode current and the nal has increased to the value E.

average value of the control-electrode current of the receiver to increase since there are developed a greater number of current pulses in a given time interval. It will be observed that the anode- .current pulse has a wave form different from proportion to the change in the quench frequency due to the similar wave form of pulses D and D.

Consider now the effect of the resistor-condenser network 31 on the operation of the superregenerative circuit'of' the present invention when the oscillation amplitude of the applied wave sig- H The inputcircuit oscillation amplitude initially tends to increase in the manner represented by curve A of Fig. 2a,. thereby shortening the quench period and increasing the control-electrod current.

"The condenser 38 thereupon tends to charge more quickly over a period of one or more but usually several quench cycles by virtue of the increase .in the average value of the control-electrode current. In doing so, the condenser 38 develops a larger negative bias for application to the control electrode of the regenerator tube II.

This larger value of bias potential decreases the transconductance of the tube H, which in turn delcreases the value of" the negative conductance developed in the tuned input circuit 12.

As a result, the oscillations in the tuned input circuit build up more slowly in amplitude, as represented by the dot-and-dash curve A of Fig. 2a. This causes the build-up interval 150-151 of the superregenerative circuit to be substantially the same for an applied wave signal of amplitude E' as' for a; wave signal of amplitude El Solid-line curve B therefore approximately represents the amplitude envelope of the oscillations developed in the tuned input circuit l2 forbotha wave signal of amplitude E and for one of amplitude E.

Similarly the solid-line curve" D approximately represents the wave form-of the coritrol-elect'rode current pulses of the tube II for applied wave signals having. amplitudes E and E. The dottedline curvev C represents the waveform of the anode-current pulse f r an input signal having the amplitude E. It will be seen that thecurrent pulse during the saturation-levelinterval is approximately identicalwith that! obtained with an input signal of amplitude EL However, the initial portion P" of the anode-current pulse represented by curveC'" 'has a somewhat lower amplitude value than the'corresponding portion Pi of the pulse of curve C. Thus the electrical-timeconstant network 31, which is responsive to control-electrode current flowing therein only during the saturation-level intervalsof-the regenerative circuit, develops and applies to; thecontrol electrode of theregenerator tube ll again-control potential whichiseifective to stabilize the operating characteristics of the receiver against changes in the average amplitude of theapplied wave signal which tend to modify theave'rage self-quench periodicity of the receiver.

By similar'analysi's it may be shown that the network 31 is effective to control theoperation of the self -quench superregenerative'receiver 'sothat the average control-electrodecurrent andthe average self-quenchfrequency are maintained substantially constant withvariationsof other operating conditions to which the receiver is normally subjected in operation. The gaincontrol potential developed by I the network 31 thus stabilizes the regenerative circuit {0 for such operating conditions as variations of the transconductance of the regenerator tube H due to aging, changes in the loading of the tuned input circuit i2 due to the antenna system in, variations of the anode-energizing potential +3, and reduces variations in operating characteristics in different radio receivers due to some component tolerances.

The position of the blade 30 of the switch 31 may be adjusted in a manner to determine the degree of stabilization of the operating characteristics of the superregenerative receiverwhich may be efiectedby the action of the network 31. Progressively greater stabilization may be realized when the switch 3| is set to close one of the switch contacts a, b', or c, in the order named. Greater stability against conditions which tend to modify the average self-quench periodicity of the receiver is provided with the switch 3| closed to its contact 0 and with the resistor 32 increased in value sufficiently to produce the same quench rate since, for a given change in the average control-electrode current of tube H, a greater change in the gain-control potential available at the control electrode is realized for providing the w against operating conditions which tend to modify'the average self-quench periodicity of the receiver, the self-quench period thereof may vary dynamically in accordance with the amplitude modulation of the received amplitude-modulated wave signal due to the low impedance of the condenser 38, at frequencies corresponding to those of themodulation components, with respect to the value of the resistor 32, and the value of the'control electrode to cathode impedance of the tube II. Thus the dynamic quench rate variesin accordance with the amplitude modulation of the received wave signal and the modulation components are derived'inthe anode circuit of the'regenerator' tube II as dynamic variations of its anode current. I

Essentially similar operation of: the superregenerative receiver is realized when the selfquench network therefor is positioned in the anode circuit of the regenerator tube I l instead of in" the" cathode circuit thereof. This type of s'elf' -quench operation may be realized by adjusting condenser 25-so that its capacitance is quite small, by moving theswitch 20 to close its contact a,-and by leaving-the remaining switches in the positions which were previously mentioned. The condenserifiand the resistor 22now determine the quench-voltage wave shape since the condenser 25"disc'harges through the anode to cathode 'space path oftheregenerator tub Ii until-the anode voltage-drops to'a level where space current ceases to flow, whereupon the condenser 25' charges through the resistor 22' from the energizing source-PB. Thus the periodic charging and discharging of the condenser 25 determines the quench-voltage wave shape. When the condenser 25 and the resistor 22 in the anode 'circuit'of'thg tube H comprise the quench determining elements for the superregenerative circuit. a' large output signal with respect to "the modulation-signal components of the applied wave signal may be realized. This results because there is no degeneration with respect to the modulation-signal components in the anode circuit of the tube II and because of the large impedance and the large current flow in the anode circuit. No degeneration takes place with this type of quench circuit because the stabilizing network may be chosen to present an impedance to audio-frequency components so low that it does not tend to stabilize with respect to audio-frequency variations in the quench rate.

When the superregenerative receiver is to be operated with both the quench determining network and the stabilizing network in the control electrode-cathode circuit of the regenerator tube 5 i, the condenser 25 is adjusted to provide a relatively large capacitance as mentioned hereinbefore, the switch 20 is operated to close its contact a, the switch 41 may be set to close either of its contacts a or 1) depending on whether the modulation components of the applied signal are to be derived from the anode circuit or the control-electrode circuit of the regenerator tube, and the switch 51 is adjusted to close its contact a or its contact as required. As previously mentioned, switch 3| may be operated to close its contact 0 for providing a maximum stabilizing action with respect to the operating character- -istics of the receiver. When the various switches are positioned as last mentioned, the network 31 effectively comprises the stabilizing network while the network 21 comprises a network for developing from the control-electrode current pulses the self-quench voltage for the receiver. The operation of the receiver when connected in this manner is much the same as that which was previously described in detail, and hence will not be repeated. Because the-resistor 29 has a high value and is effectively in series with the control electrode-cathode impedance of the tube II with respect to the flow of control-electrode current, the condenser 38 may have a relatively small value of capacitance and yet provide with the resistor 32 the necessary stabilizing action. For the anode and the cathode types of self-quenching previously described, .the condenser 38 has a relatively large value. of capacitance so that an electrolytic type condenser is ordinarily employed. However, when the self-quenching action is provided by the network 21, an: economy may be effected because of the relatively smaller capacitance value of the condenser 38. When the switch 5| is adjusted to close its contact 0 and the switch blade 42 is moved to close its contact b, the modulation components of the applied wave signal are derived from the quench-frequency determining network 21 for application to the amplifier 45. This ofiers the advantage of good audio-frequency output since no degeneration with respect to audio-frequency components appears at network 21 if the condenser 25 is increased in value to represent a low impedance at modulation frequencies, although the output signal is not as large as when it is taken from the anode of tube |l.

Under certain limiting conditions self-quench superregenerative receivers embodying the present invention ofie'r certain advantages over selfquench superregenerative receivers of the type disclosed in the above-mentioned application of Bernard D. Loughlin in which stabilization of the receiver operating characteristics is accomplished by a resistor-condenser network in the cathode circuit of the regenerator tube. A stabilizing net .workinthe cathode circuit of the regenerator 12 tube reduces the effective energizing potential applied between the anode and the cathode electrodes of the tube, thus reducing the maximum available transconductance thereof. When it is necessary to employ high-quench frequencies, improved operation results when the transconductance of the regenerator tube is high. In a typical design employing cathode-stabilizing elements of the type just mentioned, the stabilizing elements reduce the anode-cathode voltage applied to the regenerator tube by approximately 20 per cent., thus under conditions of limited available anode-energizing potential this reduction in the anode-cathode voltage may appreciably afiect the over-all operation. Since the average controlelectrode current of the self-quench superregenerative receiver is directly proportional to the quench rate thereof, it will be manifest that a self-quench superregenerative receiver embodying the present invention provides somewhat more effective stabilization of the operating characteristics against changes in the operatin conditions than has heretofore been obtainable in prior such receivers. The greater stability thereof may afford more flexibility in the choice of the wave shape of the quench voltage when particular operating characteristics of the receiver are desired to be obtained therefrom. A saving in, the cost of the components for use in the stabilization network ofthe superregenerative receiver may. also be effected, since condensers of relatively smaller capacitance may be employed in lieu of the somewhat more expensive electrolytic condensers employed in prior stabilized selfquench superregenerative receivers. Furthermore, a self-quench superregenerative receiver embodying the instant invention is suited for use at higher quench rates since the regenerator tube is operating in such a manner that the transconductance thereof is not undesirably reduced by a low anode-cathode voltage on the regenerator tube. a

While applicant does not intend to limit the invention toany particular design constants, the following values are appropriate for a particular embodiment of the invention.

Resonant frequency of I tuned input circuit 21.75 megacycles Condenser 24 2500. micromicrofarads Condenser 25 Cathode quench 0.01 microfarad Anode quench 300 micromicrofarads Control-electrode V quench 0.01 microfarad Condenser 28 500 .micromicrofarads Condenser 38 lo microfarads Resistor I3 l5 kilohms Resistor 22:

Cathode quench 22 kilohms Anode quench 33 kilohms Control-electrode V u --.-;2 -k Q m Resistor 23 1.5 kilohms Resistor 29 7 6.8 kilohms I 500 kilohms Resistor 32 (maximum) Resistor 34 "47 kilohms Resistor 35 '47 kilohms Tube H Type 1'2AT7 +B volt Approximate quench frequency V 30 kilocycles While there has beeiifd'escri bed what isat pres- "ent considere'd to'-'-be-the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing fromthe invention, and it is, therefore, aimed to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

1. A self-quench superreg'enerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including a regenerator tube having anode, cathode, and control electrodes; self-quench means coupled to said cathode electrode and having a periodic potential developed thereacross in response to an electrode-current flow of said regenerator tube for effecting periodic seliquenching of said regenerative circuit to provide superregenerative amplification of said applied wave signal; the parameters of said circuit and said self-quench means being so proportioned that the oscillatory amplitude of said circuit extends to a saturation-level mode of operation thereof during an interval of each quench cycle; an electrical time-constant network, having a time constant longer than that oi V s aid selfquench means and the periodicity of the lowest frequency modulation components of said applied wave signal, coupled in circuit with said regenerative circuit between said control electrode and cathode and responsive to control electrode current of said regenerator tube flowing only during said saturation-level intervals to develop across said network for application to said control electrode a gain-control potential elfective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average soli -quench periodicity of said receiver; and means coupled to said self-quench means for. utilizing the modulation components of said applied wave signal derived thereby.

2. A self-quench superregenerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including a regenerator tube having an anode, a cathode and a control electrode; selfquench means coupled between said cathode and a fixed potential point and having a periodic potential developed thereacross in response to the anode-cathode current flow of said regenerator tube for effecting periodic self-quenching of said regenerative circuit to provide superregenerative amplification of said applied wave signal; the parameters of said circuit and said self-quench means being so proportioned that the oscillatory amplitude of said circuit extends to a saturationlevel mode of operation thereof during an interval of each quench cycle; an electrical time-constant network, having a time constant longer than that of said self-quench means and the periodicity of the lowest frequency modulation components of said applied wave signal, coupled in circuit with said regenerative circuit between said control electrode and cathode and responsive to control-electrode current of said regenerator tube flowing only during said saturationlevel intervals to develop across said network for application to said control electrode a gain-control potential efiective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average self-quench periodicity of said receiver; and means coupled to said anode and said cathode for utilizing the high-amplitude modulation com ponents of said applied wave signal derived by said sel' f quench means;

3. A self-quench superregenerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including a regenerator tube having anode, cathode, and control electrodes; an electrical time-constant network coupled to said cathode electrode and having a periodic potential de'vel oped thereacross in response to an electrode-cur rent flow of said regenerator tube for effecting periodic self-quenching of said regenerative circult to provide superregenerative amplification of said applied wave signal; the parameters of said circuit and said network being so proportioned that the oscillatory amplitude of said circuit extends to a saturation-level mode of operation thereof during an interval or each quench cycle," an electrical time-constant network having a time constant longer than that of said first-mentioned network coupled in circuit with said regenerative circuit between said control electrode and cathode electrode and responsive to -co11trol=electrode- 'current of said regenerator tube flowing only during said saturation-level intervals to develop across said second-men'- ti'oned networkfor application to said control electrode a gain-control potential effective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average self quenchperiodicity or said receiver; and means coupled to a predeter inined 'pair of said electrodes for utilizing the modulation components of said applied wave signal er ved by Said regenerative circuit,

i. A self-quench su'perregenerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including a regenerator tube having an anode, a cathode, and a control electrode; a re- 'sistor and a condenser connected in parallel therewith coupled'to said cathode and having a periodic potential developed thereacross in response to cathode-current flow of said regenerator tube for effecting periodic self-quenching of said regenerative circuit to provide superregenerative amplification of said applied wave signal; the parameters of said circuit and said resistor and condenser being so proportioned that the oscillatory amplitude of said circuit extends to a saturation-level mode of operation thereof during an interval of each quench cycle; an electrical time-constant network having a time constant longer than that of said resistor and said condenser coupled in circuit with said regenerative circuit between said control electrod and cathode and responsive to control-electrode current of said regenerator tube flowing only during said saturation-level intervals to develop across said network for application to said control electrode a gain-control potential effective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average self-quench periodicity of said receiver; and means coupled to said anode and said cathode for utilizing the modulation components of said applied wave signal derived by said regenerative circuit.

5. A self-quench superregenerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including an oscillatory circuit and a regenerator tube having an anode, a control electrode and a cathode coupled to said oscillatory circuit;

a parallel-connected resistor-condenser network having a time constant greater than the time constant of damping of said oscillatory circuit and coupled to said cathode and. having a periodic potential developed thereacross in response to an electrode-current flow of said regenerator tube for efiecting periodic self-quenching of said regenerative circuit to provide superregenerative amplification of said applied wave signal; the parameters of said regenerative circuit and said network being so proportioned that the oscillatory amplitude of said circuit extends to a saturation-level mode of operation thereof during an interval of each quench cycle; an electrical time-constant network having a time constant longer than that of said first-mentioned network coupled in circuit with said regenerative circuit between said control electrode and cathode and responsive to control-electrode current of said regenerator tube flowing only during said saturation-level intervals to develop across said network for application to said control electrode a gain-control potential efiective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average self-quench periodicity of said receiver; and means coupled to said regenerative circuit for utilizing the modulation components of said applied wave signal derived by said regenerative circuit.

6. A self-quench superregenerative receiver comprising: a regenerative circuit adapted to have a modulated wave signal applied thereto and including an oscillatory circuit and a regenerator tube having an anode, a control electrode and a cathode coupled to said oscillatory circuit; an electrical time-constant network, having a time constant greater than the time constant of damping of said oscillatory circuit and including a resistor having a value of resistance much greater than the conductive control electrode-cathode resistance of said tube, coupled between said cathode and a fixed potential .point andhaving a periodic potential devel oped 'thereacross in response to an electrodecurrent flow of said regenerator tube for efiecting periodic self-quenching of said regenerative circuit to provide superregenerative amplification of said applied wave signal; the parameters of said regenerative circuit and said network being so proportioned that the oscillatory amplitude of said circuit extends to a saturation-level mode of operation thereof during an interval of each quench cycle; a source of positive bias potential; and an electrical time-constant network having a time constant long with respect to that of said first-mentioned network, including a condenser'having a relatively small value of capacitance, coupled in circuit with said regenerative circuit between said control electrode and said fixed potential point and to said potential source and responsive to control-electrode current flowing therein only during saturation-level intervals to develop across said second-mentioned network for application between said control electrode and said cathode a gain-control potential efiective to stabilize the operating characteristics of said receiver against operating conditions which tend to modify the average selfquench periodicity of said receiver.

DONALD RICHMAN.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,071,950 Reinartz Feb. 23, 1937 12,147,595 I-Iilferty Feb. 14, 1939 2,226,657 Bly Dec. 31, 1940 2,407,394 Birr Sept. 10, 1946 2,410,768 Worcester Nov. 5, 1946 2,410,981 Koch Nov. 12, 1946 2,412,710 Bradley Dec. 17, 1946 Bradley Apr. 18, 1950 

